Abstract: A composite photocatalyst for refractory waste treatment comprising particles of a wide band gap semiconductor material selected from the group consisting of titanium oxide, cadmium sulfide and cadmium selenide, the particles being coated with a polymer film capable of absorbing a refractory waste substrate to be treated and comprising a pyridine-containing polymer and a divalent metal porphyrin or phthalocyanine-based dye. The dye is molecularly dispersed throughout the film and chemically bonded to the pyridine-containing polymer. Upon mixing of the photocatalyst with the refractory waste substrate and irradiation with light having a wavelength of about 300 to about 400 nm, the photocalyst of the invention generates in the polymer film thereof reactive species which are sufficiently oxidizing to degrade the refractory waste substrate absorbed in the polymer film.